The present invention relates to a photoresist stripping composition and a process for stripping photoresist using the photoresist stripping composition, and more particularly, to a stripping composition for removing resist films and a process for stripping the resist films in the production of semiconductor integrated circuits and liquid crystal displays.
Photolithography has been generally employed for the production of semiconductor devices such as IC and LSI. The production of semiconductor devices by photolithography includes sequential steps of forming an insulating film such as a silicon oxide film or a conductive thin film such as a metal film for circuit wirings usually on a substrate such as silicon wafer; uniformly applying a photoresist composition on the film to form a photosensitive layer; forming desired resist patterns by selective exposure of the photosensitive layer to light and development; selectively etching the underlying thin film using the resist pattern as a mask; and then completely removing the resist pattern.
The recent demand for semiconductor devices more integrated than before requires patterns of quarter micron or smaller order. With such an extreme decrease in the processing dimension, the selective etching comes to be made mainly by a dry etching and the patterned resist comes to be removed by an oxygen-plasma asking.
However, it is well known that the dry etching process produces residues resulted from a dry-etching gas, a photoresist and an electrically conductive thin film in the periphery of the patterns. The residues will be hereinafter referred to as "resist residues." The resist residues, particularly those remaining in or around via holes, cause problems such as increase in the electrical resistance and occurrence of electrical short circuit. Therefore, it is very important for the production of semiconductor devices with high quality to remove the resist residues.
Japanese Patent Application Laid-Open Nos. 62-49355 and 64-42653 teach to remove the resist residues by organic amine stripping solutions comprising a mixture of an alkanolamine and an organic solvent. However, since the proposed stripping solutions are used at relatively high temperatures, inflammable organic compounds in the stripping solution are vaporized to likely cause bursting into flame. When a substrate cleansed with the organic amine stripping solution is rinsed with water without using an organic solvent such as alcohol, the metal film on the substrate is corroded by the alkaline nature of the remaining organic amine. Therefore, the rinsing requires the use of an organic solvent such as alcohol. To solve such problems, Japanese Patent Application Laid-Open Nos. 7-201794 and 8-20205 disclose fluorine-based aqueous solutions containing fluorine compound, organic solvent and anticorrosion agent. It is taught that the solutions have higher capability of removing the resist residues as compared with the organic amine stripping solutions, and are usable at lower temperatures.
Recent strict conditions for dry etching and asking in the production of semiconductor devices and substrates for liquid crystal display panels produce resist residues modified more complicatedly which are no longer removed completely by the above organic amine stripping solutions and fluorine-based aqueous solution. Resist residues remaining without removed cause several electrical troubles such as increase in electrical resistance, discontinuation of conductive lines, occurrence of electrical short circuits and improperly configured circuits. Therefore, a cleaning agent capable of completely removing such resist residues is strongly required.
Accordingly, it is an object of the present invention to provide a resist stripping composition which removes in a short period of time patterned resist films and resist residues remaining on an inorganic substrate after dry etching in a circuit-forming process of semiconductor devices for use in semiconductor integrated circuits or liquid crystal displays, and which causes no corrosion against various circuit materials or insulating materials. It is also an object of the present invention to provide a resist stripping process using the resist stripping composition.